1. Field of the Invention
The present invention relates to an apparatus for printing individual sheets of paper, and more particularly, to an apparatus for numbering, perforating, and printing sheets of paper.
2. Description of the Prior Art
Traditionally, "letterpress" techniques for printing sheets require reciprocating platens, and accessories must be provided for numbering and perforating the sheets. Such techniques have limitations, such as low speed, as compared with "flexographic" printing presses which utilize soft printing plates on a cylinder but are traditionally limited to printing continuous webs of paper, normally from a roll.
Offset printing, on the other hand, has been developed to incorporate rotary printing techniques with the sheet feed apparatus. Numbering devices with proper interrupters have been developed for such an offset machine as described in U.S. Pat. No. 2,683,409, Durto et al, 1954. Further, various perforating machines have been incorporated in such offset presses for perforating the sheets.
However, the numbering apparatus is normally an add-on feature and requires a second impression cylinder as with the perforator or cutting features. Furthermore, offset printing is subject to limitations which prevent it from having the versatility of printing of a letterpress or flexographic printing press.